Methods and procedures are already known, or have been proposed, for the manufacture of organic plastic parisons and finished articles via injection molding, whereby the parisons and finished articles exhibit bi-axial orientation, produced, for example, by stretching and blowing the parisons.
It is also known that the process requires transference of the parison from the injection core to a tempering mold, from the tempering mold to a stretch/blow mold, and from this to a position where the finished plastic hollow body, i.e., the stretched and blown parison, may be ejected. Of course, not all of these transfer operations may be necessary. Where they are required however, the present invention represents an improvement in conventional procedure.
For a better understanding of the present invention, it should be noted that the neck of the article under production, also referred to synonymously as the "edge" or "finish", is of great importance in carrying out any of the above-mentioned transfer operations with the desired accuracy. It must maintain its shape without distortion during each operation, and in particular, it always should remain concentric with the body of the parison.
The aim of the present invention is to protect the neck, and to prevent any distortion from occurring during the operations of transferring the parison from the mold in which it is first produced, for example by pressure molding, and accurately inserting it in any subsequent mold during the production sequence.
A further aim of the invention is to provide a seal sufficiently strong to permit application of relatively high internal pressure to the parison during the blowing stage, without the neck losing its shape.